Upgrade of zlib required to solve compilation warnings due to K&R style

When we compile aws with GNAT >= 15, we now have many compilation warnings:

/src/gnat/aws/include/zlib/uncompr.c: In function 'uncompress2':
/src/gnat/aws/include/zlib/uncompr.c:27:13: warning: old-style function definition [-Wold-style-definition]
   27 | int ZEXPORT uncompress2 (dest, destLen, source, sourceLen)
      |             ^~~~~~~~~~~
/src/gnat/aws/include/zlib/uncompr.c: In function 'uncompress':
/src/gnat/aws/include/zlib/uncompr.c:86:13: warning: old-style function definition [-Wold-style-definition]
   86 | int ZEXPORT uncompress (dest, destLen, source, sourceLen)
      |             ^~~~~~~~~~
/src/gnat/aws/include/zlib/compress.c: In function 'compress2':
/src/gnat/aws/include/zlib/compress.c:22:13: warning: old-style function definition [-Wold-style-definition]
   22 | int ZEXPORT compress2 (dest, destLen, source, sourceLen, level)
      |             ^~~~~~~~~

because the include/zlib integration corresponds to the 1.2.11 version, integrated on Feb 3 2019.

Since then, the zlib library was improved and updated to use ANSI C.
Integration of zlib 1.3.2 fixes these compilation warnings.

Start by inspecting the vendored zlib sources under include/zlib and confirm the integrated code is based on zlib 1.2.11. Update that integration to zlib 1.3.2, then compile AWS with GNAT >= 15 and verify that the K&R-style function-definition warnings are gone.